1. Field of the Invention
The invention relates to the digital signal processing of seismic data to perform certain pattern recognition techniques and, more particularly, but not by way of limitation, it relates to a process for extraction of the continuous RMS and interval velocities by examining the moveout information from common depth point traces at different offsets as measured by non-linear signal matching of selected individual traces.
2. Description of the Prior Art
The prior art methods for velocity analysis or estimation of continuous velocity determine measures of coherency, such as semblance as a function of time and velocity, as between selected seismic trace data of known offset relationship, and the velocities are then manually picked from an appropriate printout. A general discussion of the prior procedures appears in the publication "Interval Velocities From Seismic Reflection Time Measurements" - P. Hubral and T. Kray, Society of Exploration Geophysics Press, 1980. The seismic velocities can be estimated by exploiting two pieces of information, the change of reflectivity with offset, and the moveout information with offset. Most of the practical methods attempt to exploit the moveout information with offset due to the difficulties in implementation of the first mentioned procedure, i.e. attempting to establish change of reflectivity with offset. Prior methods compute contour plots of the semblance coherency measures and selected velocity relationships may then be manually picked by visual observation of the contour plots. Quantum jumps are usually made in both time and velocity variables in the computation of such contour plots. Such prior methods require an impractically large amount of computation in order to provide only poor resolution of continuous velocity estimation, and they require a considerable amount of manual involvement in order to estimate velocities for each basement point throughout the data compilation.